Finally, [1]} analysed the large-scale structure in FGs and non-FGs from both the theoretical and observational points of view. We already mentiond their theoretical results in Sect. , here we focus on their observational tests. In fact, they used four FGs selected from [2]} and coming from the 400d cluster survey [3]} and a control sample of non-FGs from the same survey. Their observational results confirmed the peak found in numerical simulations in the local density profile of galaxies around groups as a function of the normalised group-centric distance. This peak, located at about \(2.5 r/r_{vir}\)  at \(z = 0\) , is more prominent in FGs. However, the difference is clearer in numerical simulations than in observations, probably again due to the small sample of FGs available.
